Fibroblast Growth Factor Receptor 1 Amplification Research Articles

Abstract RF01-04: Final results from the phase 2, open-label FOENIX-MBC2 study: efficacy and safety of futibatinib in adult patients with locally advanced/metastatic HR+/HER2− breast cancer harboring high-level FGFR1 gene amplification

Abstract Background: Fibroblast growth factor receptor 1 (FGFR1) gene amplification and overexpression is associated with an adverse prognosis in hormone receptor–positive (HR+)/human epidermal growth factor receptor 2–negative (HER2−) breast cancer and is observed in ~10% of all invasive breast cancers. The phase 2 FOENIX-MBC2 study (NCT04024436) was designed to evaluate the effect of futibatinib, a highly selective and potent irreversible covalent inhibitor of FGFR1–4 (FDA-approved for intrahepatic cholangiocarcinoma), used either alone or in combination with fulvestrant in patients with metastatic breast cancer. Here, we report final efficacy and safety data for the cohort of patients receiving futibatinib plus fulvestrant for HR+/HER2− breast cancer harboring high-level FGFR1 gene amplification. Methods: Patients were eligible if they had disease progression after prior therapy for advanced/metastatic disease, had measurable disease per RECIST v1.1, had an ECOG performance status of 0 or 1, were fulvestrant-naïve, and had previously received 1–2 endocrine-containing therapies, ≤1 chemotherapy regimen, and a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor for advanced cancer (unless ineligible). High-level FGFR1 gene amplification, determined in tumor tissue using next-generation sequencing, fluorescence in situ hybridization (FISH), or similar assays, was defined as FGFR1/centromere 8 ratio ≥5 or FGFR1 copy number ≥10 signals per cell. Local FGFR1 determination results were confirmed in tumor tissue by a central laboratory using FISH. Patients received oral futibatinib 20 mg once daily and standard fulvestrant dosing until disease progression, unacceptable toxicity, or other discontinuation criteria were met. The primary endpoint was the 6-month progression-free survival (PFS) rate. Key secondary endpoints included objective response rate (ORR), PFS, and overall safety. Results: Overall, 22 female patients were enrolled in this cohort. Patients were a median age of 58 years, had received a median of 3 lines of any prior systemic anticancer therapy, and had all received CDK4/6 inhibitor pretreatment. PFS at 6 months was observed in 10 (45.5%) patients (95% CI: 24.4, 67.8) and the median PFS was 7.2 (95% confidence interval [CI]: 2.1, 7.6) months. Four patients had a confirmed partial response (ORR: 18.2%; 95% CI: 5.2, 40.3). The median duration of response was 6.3 (range: 3.3–12.8) months. All patients had ≥1 treatment-related adverse event (TRAE), the most common being hyperphosphatemia (95.5%), alopecia (54.5%), constipation (45.5%), and dry mouth (40.9%). There were 5 (22.7%) patients with a Grade 3 TRAE (no Grade 4 or 5). TRAEs leading to study treatment interruption or reduction were seen in 9 (40.9%) and 15 (68.2%) patients, respectively. There were 2 (9.1%) patients who had TRAEs leading to study treatment discontinuation. No treatment-related serious adverse events were reported. Conclusions: Futibatinib plus fulvestrant showed antitumor activity in patients with advanced HR+/HER2− breast cancer with FGFR1 amplification progressing on prior CDK4/6 inhibitors, with a numerically higher ORR and doubling in PFS relative to historical fulvestrant results in post-CDK4/6 patients. The safety profile was consistent with those of the individual study drugs. Further biomarker work is ongoing. Citation Format: Senthil Damodaran, Fabrice André, Nisha Unni, Marta Ferreira, Karthik Giridhar, Brooke Daniel, Marco Colleoni, Luis Costa, Thomas Bachelot, Ciara O’Brien, Gail Wright, Masashi Shimura, Gareth Tomlinson, Maciej Gil, Nicholas Turner. Final results from the phase 2, open-label FOENIX-MBC2 study: efficacy and safety of futibatinib in adult patients with locally advanced/metastatic HR+/HER2− breast cancer harboring high-level FGFR1 gene amplification [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr RF01-04.

Paradoxical cancer cell proliferation after FGFR inhibition through decreased p21 signaling in FGFR1-amplified breast cancer cells

Fibroblast growth factors (FGFs) control various cellular functions through fibroblast growth factor receptor (FGFR) activation, including proliferation, differentiation, migration, and survival. FGFR amplification in ER + breast cancer patients correlate with poor prognosis, and FGFR inhibitors are currently being tested in clinical trials. By comparing three-dimensional spheroid growth of ER + breast cancer cells with and without FGFR1 amplification, our research discovered that FGF2 treatment can paradoxically decrease proliferation in cells with FGFR1 amplification or overexpression. In contrast, FGF2 treatment in cells without FGFR1 amplification promotes classical FGFR proliferative signaling through the MAPK cascade. The growth inhibitory effect of FGF2 in FGFR1 amplified cells aligned with an increase in p21, a cell cycle inhibitor that hinders the G1 to S phase transition in the cell cycle. Additionally, FGF2 addition in FGFR1 amplified cells activated JAK-STAT signaling and promoted a stem cell-like state. FGF2-induced paradoxical effects were reversed by inhibiting p21 or the JAK-STAT pathway and with pan-FGFR inhibitors. Analysis of patient ER + breast tumor transcriptomes from the TCGA and METABRIC datasets demonstrated a strong positive association between expression of FGF2 and stemness signatures, which was further enhanced in tumors with high FGFR1 expression. Overall, our findings reveal a divergence in FGFR signaling, transitioning from a proliferative to stemness state driven by activation of JAK-STAT signaling and modulation of p21 levels. Activation of these divergent signaling pathways in FGFR amplified cancer cells and paradoxical growth effects highlight a challenge in the use of FGFR inhibitors in cancer treatment.

Abstract 6497: Molecular characterization and drug sensitivity of a gastric FGFR2-TACC2 and a pancreatic KRAS p.G12C primary culture

Abstract Introduction and Objectives: Gastric and pancreatic cancers lack effective therapies, leading to low survival rates particularly in the metastatic setting. Fibroblast growth factor receptor 2 (FGFR2) amplification and fusions with TACC2 appear in 5.5% and 2.1% of gastric tumors, respectively. In pancreatic cancers, the KRAS p.G12C mutation is limited to 1-2% of cases. FDA has recently approved drugs targeting both alterations, pemigatinib and infigratinib for cholangiocarcinoma with FGFR2 fusions; sotorasib and adagrasib for KRAS p.G12C mutant lung cancers. Here, we report the initiation of primary cultures that can be used as preclinical models for testing antitumor agents in gastric and pancreatic tumor cells. Materials and Methods: Pleural effusions were collected from a gastric and a pancreatic cancer patient, both metastatic. Cells were isolated by centrifugation, cultured for 2-3 months in complete medium and genotyped using next generation sequencing (NGS) and RNA nCounter hybridization. Primary cultures were treated with specific drugs depending on their molecular alterations and clinical guidelines. Cell viability was determined by MTT. Results: Tumor cells from the pleural effusion of the gastric cancer patient were grown in suspension. NGS and nCounter revealed a FGFR2-TACC2 fusion, a FGFR2 amplification (160 copies) and a TP53 p.G245S mutation (100% variant allele fraction, VAF). The fusion and the amplification were confirmed by FISH. Cells were sensitive to erdafitinib, with IC50=40 nM in MTT assays. Irinotecan, 5-fluorouracil and cisplatin were also tested; IC50 were below the described plasma Cmax in the first two cases. The patient was treated with first-line fluoropyrimidine and oxaliplatin with partial response and a 5-month progression-free survival. Due to rapid deterioration, 2nd line treatment was not administered. The tumor cells from the pancreatic cancer patient were adherent, NGS revealed a KRAS amplification (9 copies) accompanied by a KRAS p.G12C mutation (81% VAF) and a TP53 p.R175H mutation (99% VAF). MTT assays were performed to determine the cells’ response to oxaliplatin, 5-fluorouracil, irinotecan, gemcitabine, nab-paclitaxel, adagrasib and sotorasib. IC50s below plasma Cmax were found in the last three cases. Remarkably, the IC50 for sotorasib was 100 nM and for adagrasib was 300 nM. The patient was treated with first-line gemcitabine and nab-paclitaxel with partial response but discontinued after three months due to hematological toxicity. Conclusions: Primary cultures can be initiated from malignant pleural effusions and used for genetic characterization and drug sensitivity profiling. Primaries with specific alterations can be employed as preclinical models to test targeted therapies. Citation Format: Silvia Garcia-Roman, Ekaterina Meshoulam Nikolaeva, Juan José García Mosquera, Mónica Garzón Ibáñez, Ruth Roman, Sonia Rodríguez, Cristina Rodríguez, Clara Mayo de las Casas, Rafael Rosell, Miguel A. Molina-Vila, Cristina Aguado Esteban. Molecular characterization and drug sensitivity of a gastric FGFR2-TACC2 and a pancreatic KRAS p.G12C primary culture [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6497.

Clinical Implication of Concurrent Amplification of MET and FGFR2 in Metastatic Gastric Cancer.

c-mesenchymal epithelial transition factor receptor (c-MET) and fibroblast growth factor receptor 2 (FGFR2) amplification have been identified as factors associated with advanced stage and poor prognosis in gastric cancer (GC). While they are typically considered mutually exclusive, concurrent amplifications have been reported in a small subset of GC patients. in this retrospective study, we analyzed the clinical outcomes of GC patients with MET and FGFR2 amplification using the next-generation sequencing (NGS) database cohort at Samsung Medical Center, which included a total of 2119 patients between October 2019 and April 2021. Of 2119 cancer patients surveyed, the number of GC patients was 614 (29.0%). Out of 614 GC patients, 39 (6.4%) had FGFR2 amplification alone, 22 (3.6%) had MET amplification, and 2 GC patients (0.3%) had concurrent FGFR2 and MET amplification. Two patients with concurrent FGFR2 and MET amplification did not respond to first-line chemotherapy. These two patients had significantly shorter overall survival (3.6 months) compared to patients with FGFR2 or MET amplification alone (13.6 months and 8.4 months, respectively) (p = 0.004). Lastly, we tested the existence of FGFR2 and MET in tumor specimens from different organ sites. Initially, the NGS was tested in a primary tumor specimen from stomach cancer, where the MET copy number was 14.1 and the FGFR2 copy number was 5.3. We confirmed that both MET and FGFR2 were highly amplified in the primary tumor using FISH (MET-CEP7 ratio = 5 and FGFR2-CEP7 ratio = 3). However, although the MET copy number was normal in peritoneal seeding using FISH, FGFR2 remained amplified using FISH (FGFR2-CEP7 ratio = 7) with high FGFR2 protein overexpression. Hence, there was intra-patient molecular heterogeneity. our findings suggest that concurrent amplification of FGFR2 and MET in GC patients is associated with clinical aggressiveness and may contribute to non-responsiveness to chemotherapy or targeted therapy.

Targeting FGFR Pathway Is Not an Effective Therapeutic Strategy in Patients with Unselected Metastatic Esophagogastric Cancer Resistant to Trastuzumab

Trastuzumab plus chemotherapy is the standard of care for the first-line treatment of patients with HER2+ advanced esophagogastric (EG) cancer. Nevertheless, patients frequently develop resistance. In preclinical models, we identified the overexpression of Fibroblast Growth Factor Receptor (FGFR) 3 as a mechanism potentially involved in trastuzumab-acquired resistance. FGFR inhibition could be a potential mechanism as a second-line treatment. In this Simon's two-stage phase 2, single arm study, patients with advanced EG cancer refractory to trastuzumab-containing therapies received pemigatinib, an inhibitor of FGFR. The primary end point was the 12-week progression-free survival rate. Translational analyses were performed on tissue and plasma samples. Eight patients were enrolled in the first stage. Although the 6-week disease control rate was 25%, only one patient achieved a stable disease after 12 weeks of treatment. The trial was discontinued before the second stage. Two out of six evaluable tumor samples expressed FGFR3. No FGFRs amplification was detected. HER2 amplification was lost in three out of eight patients. Three patients had an high Tumor Mutational Burden, and two of them are significantly long-term survivors. These results do not support the therapeutic efficacy of targeting FGFR in unselected patients with advanced EG cancer, who are refractory to trastuzumab-containing therapies.

Targeting FGFR2 Positive Gastroesophageal Cancer: Current and Clinical Developments.

Despite recent advances in the systemic treatment of gastroesophageal cancers, prognosis remains poor. Comprehensive molecular analyses have characterized the genomic landscape of gastroesophageal cancer that has established therapeutic targets such as human epidermal growth factor receptor 2 (HER2), vascular endothelial growth factor receptor (VEGFR) and programmed death ligand 1 (PD-L1). The aberrant fibroblast growth factor receptor 2 (FGFR2) pathway is attractive for targetable therapy with FGFR inhibition based on preclinical data showing a pivotal role in the progression of gastric cancer (GC). FGFR2 amplification is the most common FGFR2 gene aberration in gastroesophageal cancer, and most associated with diffuse GC, which is often linked to poorer prognostic outcomes. There has been considerable progress with drug development focused on FGFR inhibition. At present, there is no approved FGFR inhibitor for FGFR2 positive gastroesophageal cancer. A selective FGFR2b monoclonal antibody bemarituzumab is currently being investigated in the first phase III randomized trial for patients with first line advanced GC, which may change the treatment paradigm for FGFR2b positive GC. The role of FGFR signalling, specifically FGFR2, is less established in oesophageal squamous cell cancer (ESCC) with a paucity of evidence for clinical benefit in these patients. Precision medicine is part of the wider approach in gastrointestinal cancers; however, it can be challenging due to heterogeneity and here circulating tumour DNA (ctDNA) for patient selection may have future clinical utility. In our review, we outline the FGFR pathway and focus on the developments and challenges of targeting FGFR2 driven gastroesophageal cancers.

Peritoneal Seeding Is More Common in Gastric Cancer Patients with FGFR2 Amplification or High Tumor Mutation Burden.

Fibroblast growth factor receptor-2 (FGFR2) gene alterations have been identified in solid tumors. FGFR2 amplification is found in 2–9% of gastric carcinomas. We hypothesized that FGFR2 could be associated with peritoneal seeding and studied 360 advanced gastric carcinoma patients; 222 (61.7%) were male, 246 (73.7%) had poorly differentiated histology, and 175 (48.6%) presented with peritoneal seeding. High tumor mutation burden (TMB) was observed in 44 (12.2%) patients, high microsatellite instability (MSI) was observed in 12 (3.33%) patients, ERBB2 amplification was observed in 44 (12.2%) patients, EBV positivity was observed in 10 (10/278; 3.6%) patients, and PD-L1 positivity was observed in 186 (186/264; 70.5%) cases. We found FGFR2 amplification in 26 (7.2%) patients, of which 12 (46.2%) were female and 22 (84.6%) had poorly differentiated histology. In these 26 cases, the copy number of FGFR2 amplification ranged from 3.7 to 274. Eighteen of them showed seeding, and this association was statistically significant (18/26, 69.2%; 157/334, 47%; p = 0.023). In addition, high TMB was significantly associated with seeding (p = 0.028; OR = 1.83). Poorly differentiated histology was significantly associated with seeding (p = 0.04) but not with FGFR2 amplification (p > 0.1). Seeding was frequent in gastric carcinoma patients with FGFR2 amplification, in patients with high TMB, or in those who were female. The subgroup of patients with FGFR2 amplification could be potential candidates for targeted therapeutic agents.

Abstract 167: Pre-clinical characterization of a novel series of FGFR2 selective inhibitors with potency against clinically relevant mutations

Abstract The fibroblast growth factor receptor (FGFR) family of protein tyrosine kinases plays a role in many physiological processes including angiogenesis and wound healing. FGFR mutations, fusions, rearrangements, and amplifications have been linked to the pathogenesis of multiple tumor types. For example, approximately 10-15% of patients with intrahepatic cholangiocarcinoma have FGFR2 fusions, and amplification of FGFR2 is prevalent in gastric cancer and implicated in tumor growth. Approved FGFR inhibitors produce responses in patients that harbor FGFR genetic alterations but show reduced activity against key mutations (e.g., V565, N550, etc.). These pan-FGFR inhibitors also frequently show dose-limiting toxicities including hyperphosphatemia which can be linked to the inhibition of FGFR1. To address these issues, a novel series of FGFR inhibitors that are potent and selective reversible inhibitors of FGFR2 with selectivity over FGFR1 have been identified. This series also maintains activity against clinically relevant mutations in the FGFR2 protein. Inhibition of cellular FGFR phosphorylation was measured using engineered cell lines to demonstrate that the inhibitors target both wild-type FGFR2 and activating FGFR2 mutations while sparing FGFR1. In addition, CDX tumor models showed in vivo target engagement and FGFR isoform selectivity. Herein, the in vitro and in vivo characterization of a representative selective reversible FGFR2 inhibitor is described. Citation Format: John Fischer, Karyn Bouhana, Mark J. Chicarelli, Josh Dahlke, Brad Fell, Jennifer Fulton, Anna Guarnieri, Ravi Jalluri, Amber Johnson, Brent Mclean, Max Mejia, Rob Rieger, John Robinson, Mareli Rodriguez, Francis Sullivan, Yang Wang, Shannon Winski, Yeyun Zhou. Pre-clinical characterization of a novel series of FGFR2 selective inhibitors with potency against clinically relevant mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 167.

Incidence of FGFR2 Amplification and FGFR2 Fusion in Patients with Metastatic Cancer Using Clinical Sequencing.

Aberrations in the fibroblast growth factor receptor2 (FGFR2) gene, including genetic alterations and chromosomal rearrangements, lead to the development and progression of cancer with poor prognosis. However, the mechanisms underlying the FGFR2 signaling pathway to facilitate the development of FGFR2-targeted therapies have not been fully explored. Here, we examined the clinicopathological features of FGFR2 amplification and fusion in gastrointestinal tract/genitourinary tract cancers. FGFR2 amplification and fusion were identified in approximately 1.5% and 1.1% of all cancer types in 1,373 patients, respectively, with both FGFR2 amplification and fusion occurring together at a rate of approximately 0.6%. Of all cancer types screened, gastric cancer (GC) was the most common cancer type with FGFR2 amplification (87.5% of all FGFR2 amplification case) or fusion (46.7% of all cases). In addition, FGFR2 alteration had poorer overall survival (OS, 13.7 months vs. 50.2 months, P = 0.0001) and progression-free survival (PFS, 5.6 months vs. 11.4 months, P = 0.0005) than did those without FGFR2 alteration, respectively. Taken together, our data underscore to screen solid cancer patients for FGFR2 aberrations in oncology clinic.

Abstract P3-08-02: The frequency and somatic mutation landscape of Fibroblast growth factor receptor (FGFR) alterations in breast cancer

Abstract Background: FGFR dysregulation is observed in multiple cancers and targeting FGFR is an emerging therapeutic strategy with FDA approved treatments in bladder and cholangiocarcinoma. Here we examined the prevalence of FGFR mutations, fusions, and high-level amplifications in breast cancer, stratified by receptor subtype and local/metastatic status, in both Foundation Medicine (FM) and institutional Mayo Clinic (MC) cohorts. Methods: For the FM cohort, comprehensive genomic profiling (CGP) examining at least 324 genes for all classes of alterations, including FGFR1-4 was carried out for 32,048 breast cancers during the course of routine clinical care in a Clinical Laboratory Improvement Amendments (CLIA)-certified lab (Foundation Medicine Inc., Cambridge, MA, USA). Tumor mutational burden (TMB) was determined on up to 1.1 Mb, microsatellite instability high (MSI-High) was determined on up to 114 loci and predicted ancestry from >10,000 SNPs. Estrogen receptor (ER) and HER2 status were available for a subset of FM samples. Additionally, 131 patients with metastatic breast cancer from a subset of patients at three Mayo Clinic sites (MC cohort) with clinical characteristics and cancer-panel DNA sequencing data from a CLIA-certified lab (Tempus, Chicago, IL) were included. Results: In the FM cohort, the prevalence of FGFR1-4 high-level amplification (CN≥10) was 10.1%, while mutations (1.5%) and fusions (0.72%) were rare. Most amplifications occurred in FGFR1 (9.2%); most fusions and mutations occurred in FGFR2 (0.46%, 0.77%). FGFR alteration prevalence was highest in ER+/HER2- subtype (14.4%) and lowest in HER2+ disease (7.7%). FGFR alterations were more common in IDC (11.7%) than ILC (7.7%), p<3E-08. FGFR alterations were more prevalent in the metastatic setting relative to breast-biopsied disease (13.6% v 10.1%; OR = 1.4; p=2E-17), especially in the HER2+ (OR =1.9, p=0.004) and ER-/HER2- (OR = 1.9, p = 0.05) disease; no enrichment was seen in the ER+/HER2- metastases (OR =1.0, p = 1). FGFR amplifications were observed at a higher prevalence in patients with predicted East Asian ancestry, relative to patients with European ancestry (12.1% v 10.0%; p = 0.03). Overall, the most common activating mutations in FGFR were FGFR2 N549K (n=85), FGFR1 N546K (n=78), FGFR4 V510M (n=28), FGFR2 K659E (n=28), FGFR4 V510L (n=20), and FGFR2 Y375C (n=15). The most common recurrent fusions were FGFR3:TACC3 (n=36), FGFR2:TACC2 (n=17), FGFR1:TACC1 (n=9), FGFR1:BAG4 (n=6), and FGFR2:ATE1 (n=5). In patients with FGFR amplifications, the most frequently co-occurring alterations were ZNF703 (78.4%), TP53 (51.5%), CCND1 (36.1%), FGF3/4/19 (32.9 - 34.4%), PIK3CA (30.7%), MYC (29.6%), ESR1 (17.2%), EMSY (16.3%), and PTEN (10.6%). Significant co-occurrence was observed for a number of genes including FGF3/4/19, CDK4, and CDK8 (all OR>2, p<1E-07); mutual exclusivity was observed with PIK3R1, BRCA1, and BRCA2 (all OR <0.5, p<4E-13), among other genes. In the 131 metastatic tumors from MC, the prevalence of FGFR1-4 high-level amplifications was 19.8% [FGFR1 (12.4%), FGFR2 (7.4%), and FGFR3 (0.8%)]. The prevalence of high-level FGFR amplifications did not differ by clinical subtypes: HR-/HER2- (7/31), HR+/HER2- (15/79), and HER2+ (2/11), p=0.68. Conclusions: High-level FGFR amplifications are observed in >11% of breast cancers, especially the ER+/HER2- subtype, while mutations/fusions are rare. These data support the ongoing studies evaluating targeted therapies for FGFR amplified ER + breast cancer. Correlations with clinical information (MC cohort) and associations with actionable alterations are ongoing and may inform potential combination strategies. Citation Format: Karthik V Giridhar, Ethan S Sokol, Peter T Vedell, Jason P Sinnwell, Aakash Desai, Tufia C Haddad, Ciara C O’Sullivan, Roberto A Leon-Ferre, Siddhartha Yadav, Kostandinos Sideras, Brenda Ernst, Minetta C Liu, Abe Eyman Casey, Xiaojia Tang, Zoe Fleischmann, Karthikeyan Murugesan, Krishna R Kalari, Matthew P Goetz. The frequency and somatic mutation landscape of Fibroblast growth factor receptor (FGFR) alterations in breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-08-02.

A phase 1 study evaluating preliminary safety, pharmacokinetic and pharmacodynamic of pemigatinib in Chinese patients with advanced malignancy.

e15051 Background: Dysregulation of fibroblast growth factor receptor (FGFR) is strongly associated with establishment and progression of cancer. Pemigatinib is a selective FGFR1–3 inhibitor that are active in a targeted manner against cancers with activated FGFR pathway. The study was aimed at evaluating the tolerability, pharmacokinetic (PK) and pharmacodynamic (PD) of pemigatinib in Chinese patients (pts) with advanced malignancy. Moreover, potential efficacy of pemigatinib was explored in a broad spectrum of FGFR alteration in variety of cancer types. Methods: In this phase 1 study, Chinese patients with advanced, recurrent or metastatic malignancy that were histologically or cytologically confirmed and harboring FGF/ FGFR 1-3 variation were enrolled. Pemigatinib was self-administered orally at 13.5 mg QD on a 3-week cycle (2-weeks-on/1-week-off schedule). Adverse events and other safety factors were monitored throughout the study. Blood samples were obtained at prespecified time points for PK and PD analysis and efficacy was assessed every 9 weeks per RECIST v1.1 guideline. Results: As of Jan 31, 2021, 12 patients with 5 different cancer types (colorectal cancer (4 pts), gastric and gastroesophageal junction carcinoma (3 pts), cholangiocarcinoma (2 pts), esophageal carcinoma (2 pts) and breast cancer (1pts)) were enrolled. Documented FGF/ FGFR1-3 alterations were FGFR amplification (6), FGFR point mutation (5), FGFR2 fusion (2) and FGF alteration (4) with 2 subjects had more than one alteration types. All the subjects were failed to at least 1 line of prior standard therapy. All patients had at least 1 treatment related adverse events (TRAE) and the most common ones were hyperphosphatemia (100%), decreased appetite (50%) and diarrhea (33.3%). Two patients (16.7%) reported ≥ grade 3 TRAEs, which were hyponatremia (8.3%) and proteinuria (8.3%). There were no TEAEs leading to death or treatment discontinuation. Among 11 efficacy evaluable patients, 2 of them had partial responses (PR) as evaluated by investigators with 1 cholagiocarcinoma harboring FGFR2 point mutation (p.F276C) and the other esophageal carcinoma carrying FGFR1 mutation (p.A354V). 3 patients had a best overall response of stable disease (SD). The objective response rate (ORR) was 16.7% (95%CI: 2–48%) and disease control rate was 41.7% (95%CI: 15–72%). Conclusions: Pemigatinib had an acceptable and manageable toxicity and demonstrated a possible anti-cancer benefit in Chinese patients with advanced malignancy that accompanied with FGF/FGFR1-3 aberrance. A significant implication of the data is that it extended the population that potentially benefit from pemigatinib other than FGFR2 fusion/rearrangement. Clinical trial information: NCT04258527.

Prognostic value of FGFR1 expression and amplification in patients with HNSCC: A systematic review and meta-analysis.

Fibroblast growth factor receptor 1 (FGFR1) has recently been identified as a promising novel therapeutic target and prognostic marker in different types of cancer. In the present study, a meta-analysis was performed to clarify the correlation between FGFR1 and the survival outcomes of head and neck squamous cell carcinoma (HNSCC) patients. PubMed, Embase, and Web of Science were systematically searched for relevant studies in order to explore the prognostic significance of FGFR1 in HNSCC. Hazards ratios (HR) and 95% confidence intervals (CI) were collected to estimate the correlation between overexpression and amplification of FGFR1 and survival outcomes of HNSCC patients. Nine studies including 2708 patients with HNSCC were finally selected for the meta-analysis. The results indicated that FGFR1 predicted poor overall survival (OS) (HR, 1.97; 95% CI, 1.49–2.61, P<0.001) in HNSCC patients. Futhermore, FGFR1 was related to poor OS in human papillomavirus (HPV) negative HNSCC not in HPV positive HNSCC patients. Subgroup analysis stratified by molecular abnormalities, such as overexpression or amplification showed the similar results. The present study demonstrated that HNSCC patients with FGFR1 overexpression and amplification were more likely to exhibit poorer survival.

FGFR1 overexpression in non-small cell lung cancer is mediated by genetic and epigenetic mechanisms and is a determinant of FGFR1 inhibitor response

Amplification of fibroblast growth factor receptor 1 (FGFR1) in non-small cell lung cancer (NSCLC) has been considered as an actionable drug target. However, pan-FGFR tyrosine kinase inhibitors did not demonstrate convincing clinical efficacy in FGFR1-amplified NSCLC patients. This study aimed to characterise the molecular context of FGFR1 expression and to define biomarkers predictive of FGFR1 inhibitor response.In this study, 635 NSCLC samples were characterised for FGFR1 protein expression by immunohistochemistry and copy number gain (CNG) by in situ hybridisation (n = 298) or DNA microarray (n = 189). FGFR1 gene expression (n = 369) and immune cell profiles (n = 309) were also examined. Furthermore, gene expression, methylation and microRNA data from The Cancer Genome Atlas (TCGA) were compared. A panel of FGFR1-amplified NSCLC patient-derived xenograft (PDX) models were tested for response to the selective FGFR1 antagonist M6123.A minority of patients demonstrated FGFR1 CNG (10.5%) or increased FGFR1 mRNA (8.7%) and protein expression (4.4%). FGFR1 CNG correlated weakly with FGFR1 gene and protein expression. Tumours overexpressing FGFR1 protein were typically devoid of driver alterations (e.g. EGFR, KRAS) and showed reduced infiltration of T-lymphocytes and lower PD-L1 expression. Promoter methylation and microRNA were identified as regulators of FGFR1 expression in NSCLC and other cancers. Finally, NSCLC PDX models demonstrating FGFR1 amplification and FGFR1 protein overexpression were sensitive to M6123.The unique molecular and immune features of tumours with high FGFR1 expression provide a rationale to stratify patients in future clinical trials of FGFR1 pathway-targeting agents.

Clinical difference between fibroblast growth factor receptor 2 subclass, type IIIb and type IIIc, in gastric cancer

Fibroblast growth factor receptor 2 (FGFR2) has two isoforms: IIIb type and IIIc type. Clinicopathologic significance of these two FGFR2 subtypes in gastric cancer remains to be known. This study aimed to clarify the clinicopathologic difference of FGFR2IIIb and/or FGFR2IIIc overexpression. A total of 562 patients who underwent gastrectomy was enrolled. The expressions of FGFR2IIIb and FGFR2IIIc were retrospectively examined by immunohistochemistry or fluorescence in situ hybridization (FISH) using the 562 gastric tumors. We evaluated the correlation between clinicopathologic features and FGFR2IIIb overexpression and/or FGFR2IIIc overexpression in gastric cancer. FGFR2IIIb overexpression was observed in 28 cases (4.9%), and FGFR2IIIc overexpression was observed in four cases (0.7%). All four FGFR2IIIc cases were also positive for FGFR2IIIb, but not in the same cancer cells. FGFR2IIIb and/or FGFR2IIIc overexpression was significantly correlated with lymph node metastasis and clinical stage. Both FGFR2IIIb and FGFR2IIIc were significantly associated with poor overall survival. A multivariate analysis showed that FGFR2IIIc expression was significantly correlated with overall survival. FISH analysis indicated that FGFR2 amplification was correlated with FGFR2IIIb and/or FGFR2IIIc overexpression. These findings suggested that gastric tumor overexpressed FGFR2IIIc and/or FGFR2IIIb at the frequency of 4.9%. FGFR2IIIc overexpression might be independent prognostic factor for patients with gastric cancer.

A comparative study of RTK gene status between primary tumors, lymph-node metastases, and Krukenberg tumors

Krukenberg tumor (KT) refers to a rare ovarian tumor that has metastasized from a primary site. Patients with KTs have a poorer prognosis and worse survival. Thus far, little is known about the frequency of receptor tyrosine kinase (RTK) gene amplification and the concordance of gene amplification between primary tumors, lymph-node metastases, and KTs. Herein, 50 paired samples, including primary cancers, metastatic lymph nodes, and KTs were collected, and RTK gene amplification was tested by fluorescence in situ hybridization (FISH). There were four cases positive for human epidermal growth factor receptor type 2 (HER2) amplification, all of which showed conversion of HER2 status between different lesions. Of the two cases with c-mesenchymal–epithelial transition (c-MET) amplification, the primary tumors and lymph nodes were negative while the right involved ovaries were positive. Inconsistent fibroblast growth factor receptor 2 (FGFR2) status in different lesions was observed in three of the six FGFR2-amplified cases. Co-amplification of RTK genes was identified in only one patient for primary cancer and two for KTs. Collectively, there were 46, 48, 50, and 44 cases negative for HER2, c-MET, EGFR, and FGFR2 amplification in all lesions, respectively. There was no significant difference in overall survival between KTs of gastric origin and colorectal origin. However, of all synchronous cancers, KTs of colorectal origin had a better prognosis than those of gastric origin. In conclusion, the positive rate of RTK gene amplification in KTs was low. Intratumoral heterogeneity was frequent in KTs with RTK gene amplification. A mutually exclusive pattern of RTK gene amplification was dominant in primary cancers, lymph-node metastases, and KTs. There was no survival difference between KTs of gastric origin and colorectal origin. However, of all synchronous cancers, KTs of colorectal origin had a better prognosis than those of gastric origin.

Targeting FGFR in non-small cell lung cancer: implications from the landscape of clinically actionable aberrations of FGFR kinases.

Objective:Dysfunction in fibroblast growth factor receptor (FGFR) signaling has been reported in diverse cancer types, including non-small cell lung cancer (NSCLC). The frequency of FGFR aberrations in Chinese NSCLC patients is therefore of great clinical significance.Methods:A total of 10,966 NSCLC patients whose tumor specimen and/or circulating cell-free DNA (cfDNA) underwent hybridization capture-based next-generation sequencing were reviewed. Patients’ clinical characteristics and treatment histories were also evaluated.Results:FGFR aberrations, including mutations, fusions, and gene amplifications, were detected in 1.9% (210/10,966) of the population. FGFR abnormalities were more frequently observed in lung squamous cell carcinomas (6.8%, 65/954) than lung adenocarcinomas (1.3%, 128/9,596). FGFR oncogenic mutations were identified in 19 patients (∼0.17%), of which, 68% were male lung squamous cell carcinoma patients. Eleven out of the 19 patients (58%) had concurrent altered PI3K signaling, thus highlighting a potential combination therapeutic strategy of dual-targeting FGFR and PI3K signaling in such patients. Furthermore, FGFR fusions retaining the intact kinase domain were identified in 12 patients (0.11%), including 9 FGFR3-TACC3, 1 FGFR2-INA, 1 novel FGFR4-RAPGEFL1, and 1 novel fusion between the FGFR1 and SLC20A2 5′-untranslated regions, which may have caused FGFR1 overexpressions. Concomitant EGFR mutations or amplifications were observed in 6 patients, and 4 patients received anti-EGFR inhibitors, in whom FGFR fusions may have mediated resistance to anti-EGFR therapies. FGFR amplification was detected in 24 patients, with the majority being FGFR1 amplifications. Importantly, FGFR oncogenic mutations, fusions, and gene amplifications were almost always mutually exclusive events.Conclusions:We report the prevalence of FGFR anomalies in a large NSCLC population, including mutations, gene amplifications, and novel FGFR fusions.

FGFR1 Is Critical for RBL2 Loss-Driven Tumor Development and Requires PLCG1 Activation for Continued Growth of Small Cell Lung Cancer.

Small cell lung cancer (SCLC) remains a recalcitrant disease where limited therapeutic options have not improved overall survival, and approved targeted therapies are lacking. Amplification of the tyrosine kinase receptor FGFR1 (fibroblast growth factor receptor 1) is one of the few actionable alterations found in the SCLC genome. However, efforts to develop targeted therapies for FGFR1-amplified SCLC are hindered by critical gaps in knowledge around the molecular origins and mediators of FGFR1-driven signaling as well as the physiologic impact of targeting FGFR1. Here we show that increased FGFR1 promotes tumorigenic progression in precancerous neuroendocrine cells and is required for SCLC development in vivo. Notably, Fgfr1 knockout suppressed tumor development in a mouse model lacking the retinoblastoma-like protein 2 (Rbl2) tumor suppressor gene but did not affect a model with wild-type Rbl2. In support of a functional interaction between these two genes, loss of RBL2 induced FGFR1 expression and restoration of RBL2 repressed it, suggesting a novel role for RBL2 as a regulator of FGFR1 in SCLC. Additionally, FGFR1 activated phospholipase C gamma 1 (PLCG1), whereas chemical inhibition of PLCG1 suppressed SCLC growth, implicating PLCG1 as an effector of FGFR1 signaling in SCLC. Collectively, this study uncovers mechanisms underlying FGFR1-driven SCLC that involve RBL2 upstream and PLCG1 downstream, thus providing potential biomarkers for anti-FGFR1 therapy. SIGNIFICANCE: This study identifies RBL2 and PLCG1 as critical components of amplified FGFR1 signaling in SCLC, thus representing potential targets for biomarker analysis and therapeutic development in this disease.

A comprehensive pan-cancer study of fibroblast growth factor receptor aberrations in Chinese cancer patients.

BackgroundThe prevalence and types of fibroblast growth factor receptor (FGFR) mutations vary significantly among different ethnic groups. The optimal application of FGFR inhibitors depends on these variations being comprehensively understood. However, such an analysis has yet to be conducted in Chinese patients.MethodsWe retrospectively screened the genomic profiling results of 10,582 Chinese cancer patients across 16 cancer types to investigate the frequency and distribution of FGFR aberrations.ResultsFGFR aberrations were identified in 745 patients, equating to an overall prevalence of 7.0%. A majority of the aberrations occurred on FGFR1 (56.8%), which was followed by FGFR3 (17.7%), FGFR2 (14.4%), and FGFR4 (2.8%). Further, 8.5% of patients had aberrations of more than 1 FGFR gene. The most common types of aberrations were amplification (53.7%), other mutations (38.8%), and fusions (5.6%). FGFR fusion and amplification occurred concurrently in 1.9% of the patients. FGFR aberrations were detected in 12 of the 16 cancers, with the highest prevalence belonging to colorectal cancer (CRC) (31%). Other FGFR-aberrant cancer types included stomach (16.8%), breast (14.3%), and esophageal (12.7%) cancer. Breast tumors were also more likely than other cancer types to have concurrent FGFR rearrangements and amplifications (P<0.001). In comparison with the public dataset, our cohort had a significantly higher number of FGFR aberrations in colorectal (P<0.001) and breast cancer (P=0.05).ConclusionsAmong the Chinese cancer patients in our study, the overall prevalence of FGFR aberrations was 7.0%. FGFR1 amplification was the most common genetic alteration in CRC, breast cancer, and lung cancer; while FGFR2 amplification was more commonly observed in gastric cancer than in other cancers in our cohort. Our study advances the understanding of the distribution of FGFR aberrations in various cancer types in the Chinese population, which will facilitate the further development of FGFR inhibitors.

A novel monovalent FGFR1 antagonist: Preclinical safety profiles in rodents and non-human primates

Blocking Fibroblast Growth Factor Receptor 1 (FGFR1) is an attractive therapeutic option for treatment of cancer subtypes with amplification and over-expression of FGFR1. Selective targeting of FGFR1 can be achieved using an antibody-based approach, as small molecule inhibitors may not discriminate between FGFR1, 2, 3 and 4 due to their highly homologous kinase domain. However, development of classical bivalent FGFR1 directed antibodies has failed due to non-tolerated body weight decreases in preclinical species. M6123 is a novel IgG-like monovalent FGFR1 specific binder with enhanced Antibody-Dependent Cellular Cytotoxicity (ADCC) effector function and inhibits tumor growth significantly in FGFR1-dependent human xenograft models without reduced body weight in tumor-bearing mice. Toxicology studies reported here characterized the safety profile of M6123 in mouse, rat, and monkey. There were significant differences among animal species under similar M6123 exposure levels. Rats showed metastatic mineralization with an imbalance in serum phosphate at low doses, while mineralization was not found in mice or monkeys, even though hyperphosphatemia was detected in mice. Subtle differences in calcium/phosphate homoeostasis feedback loops may trigger the susceptibility to mineralization among animal species; nevertheless, the exact mechanism remains unknown. Monkeys showed marked, but reversible, decreases in peripheral blood NK cells and neutrophils. The latter was associated with considerably increased neutrophilic infiltrates in the liver sinusoids and red pulp of the spleen. These effects in monkeys are likely related to the enhanced ADCC activity of M6123. Overall, M6123 showed a superior safety profile in animals compared to bivalent FGFR1 antagonists or pan-FGFR inhibitors.

Impact of fibroblast growth factor receptor 1 (FGFR1) amplification on the prognosis of breast cancer patients

PurposeVarious aberrations in the fibroblast growth factor receptor genes FGFR1, FGFR2, and FGFR3 are found in different cancers, including breast cancer (BC). This study analyzed the impact of FGFR amplification on the BC prognosis.MethodsThe study included 894 BC patients. The amplification rates of FGFR1, FGFR2, and FGFR3 were evaluated on tissue microarrays using fluorescence in situ hybridization (FISH). Associations between these parameters and prognosis were analyzed using multivariate Cox regression analyses.ResultsFGFR1 FISH was assessable in 503 samples, FGFR2 FISH in 447, and FGFR3 FISH in 562. The FGFR1 amplification rate was 6.6% (n = 33). Increased FGFR2 copy numbers were seen in 0.9% (n = 4); only one patient had FGFR3 amplification (0.2%). Most patients with FGFR1 amplification had luminal B-like tumors (69.7%, n = 23); only 32.6% (n = 153) of patients without FGFR1 amplification had luminal B-like BC. Other patient and tumor characteristics appeared similar between these two groups. Observed outcome differences between BC patients with and without FGFR1 amplification did not achieve statistical significance; however, there was a trend toward poorer distant metastasis-free survival in BC patients with FGFR1 amplification (HR = 2.08; 95% CI 0.98 to 4.39, P = 0.05).ConclusionFGFR1 amplification occurs most frequently in patients with luminal B-like BC. The study showed a nonsignificant correlation with the prognosis, probably due to the small sample size. Further research is therefore needed to address the role of FGFR1 amplifications in early BC patients. FGFR2 and FGFR3 amplifications are rare in patients with primary BC.